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Oxidation of KCNB1 potassium channels triggers apoptotic integrin signaling in the brain
Wei Yu1, Manasa Gowda1, Yashsavi Sharad1
1Department of Neuroscience and Cell Biology, Rutgers University, Robert Wood Johnson Medical School, 683 Hoes Lane West, Piscataway, NJ, USA.
Abstract:
Oxidative modification of the voltage-gated potassium (K+) channel KCNB1 promotes apoptosis in the neurons of cortex and hippocampus through a signaling pathway mediated by Src tyrosine kinases. How oxidation of the channel is transduced into Src recruitment and activation, however, was not known. Here we show that the apoptotic signal originates from integrins, which form macromolecular complexes with KCNB1 channels. The initial stimulus is transduced to Fyn and possibly other Src family members by focal adhesion kinase (FAK). Thus KCNB1 and integrin alpha chain V (integrin-α5) coimmunoprecipitated in the mouse brain and these interactions were retained upon channel's oxidation. Pharmacological inhibition of integrin signaling or FAK suppressed apoptosis induced by oxidation of KCNB1, as well as FAK and Src/Fyn activation. Most importantly, the activation of the integrin-FAK-Src/Fyn cascade was negligible in the presence of non-oxidizable C73A KCNB1 mutant channels, even though they normally interacted with integrin-α5. This leads us to conclude that the transition between the non-oxidized and oxidized state of KCNB1 activates integrin signaling. KCNB1 oxidation may favor integrin clustering, thereby facilitating the recruitment and activation of FAK and Src/Fyn kinases.
Insights
Oxidative modification of the KCNB1 potassium channel triggers neuronal apoptosis via integrin signaling. This pathway involves focal adhesion kinase (FAK) and Src/Fyn kinases, linking channel oxidation to cell death.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Oxidative modification of voltage-gated potassium (KCNB1) channels promotes neuronal apoptosis.
- The precise mechanism linking KCNB1 oxidation to Src tyrosine kinase activation remained unclear.
Purpose of the Study:
- To elucidate the signaling pathway mediating apoptosis induced by KCNB1 oxidation.
- To identify the upstream components involved in transducing the oxidative signal to Src kinases.
Main Methods:
- Co-immunoprecipitation assays in mouse brain to assess KCNB1 and integrin interactions.
- Pharmacological inhibition of integrin signaling and focal adhesion kinase (FAK).
- Assessment of apoptosis, FAK, and Src/Fyn activation in response to KCNB1 oxidation and inhibition.
Main Results:
- KCNB1 channels form complexes with integrin alpha chain V (integrin-α5), which are maintained upon channel oxidation.
- Inhibition of integrin signaling or FAK suppressed KCNB1 oxidation-induced apoptosis and kinase activation.
- A non-oxidizable KCNB1 mutant (C73A) failed to activate the integrin-FAK-Src/Fyn cascade, despite normal integrin interaction.
Conclusions:
- Oxidation of KCNB1 channels activates the integrin-FAK-Src/Fyn signaling cascade, leading to neuronal apoptosis.
- KCNB1 oxidation likely promotes integrin clustering, facilitating the recruitment and activation of FAK and Src/Fyn kinases.